Preheat oven to 450°. To crumble the chocolate cookie crumbs, place in a food processor and pulse a few times until the crumbs are fine.  Add sugar and melted butter and process until mixture is combined.

Press into the bottom of a 9" pie plate.  Place another pie plate the same size or smaller on top to press the crumbs into place.

Place crust in a preheated 450° oven for 5 minutes.  Set aside to cool.

To make the Ganache, heat the cream in a saucepan. Remove from heat, add chocolate and let it sit for a few minutes.  Then stir until completely combined.   Drop spoonfuls of the ganache in the center of the cooled pie shell.  Using an offset spatula, spread the ganache from the center outward and up the sides of the pie shell.  Chill the crust until the ganache is set.

Make the Peanut Butter Mousse: In a medium bowl, combine powdered sugar, peanut butter, cream cheese and vanilla and mix at medium-high speed until the mixture is light and fluffy.  In a separate bowl, whip the cream until you have stiff peaks. Fold the whipped cream into the peanut butter mixture with a rubber spatula carefully and slowly, until the mixture is combined, but no more.

If desired, place about 3/4 cup of the peanut butter mousse into a piping bag fitted with a star tip.  Fill the pie with the remaining mousse, smoothing the top with a rubber spatula.  Pipe the star kisses around the edge of the pie to decorate.

With a box grater sitting on a plate, grate the chocolate bar on the large grating edge. To make it easier, you can place the bar in the microwave for about 5 seconds to soften without melting it. Sprinkle the grated chocolate over the center of the pie without touching the piped kisses.  Refrigerate the pie for at least 2 hours before serving.